For operating a terminal device, for example a mobile cellular telephone, a smartphone or a tablet PC, in a wireless communication system, for example a telecommunication network comprising cellular data communication and telephony communication, the total battery life can be a crucial factor and may be one of the main performance indicators from a consumer's perspective. The time between required battery charges significantly impacts the consumer behavior and use case possibilities.
For telephony communication a transceiver unit of the terminal device, a so-called modem, is activated for receiving or initiating a call and is deactivated when the call is ended. However, when a data transfer occurs in a mobile communication network between the network or a base station of the network and the terminal device, for example for receiving or sending e-mails or uploading and downloading information to the internet, this activity will impact the average modem power consumption, especially in case the terminal is otherwise in dormant state. The reason for this is not only the power consumption during the data transfer itself, but also because usually the modem is forced to stay in a power consuming state for a certain time after each data activity, for example for avoiding frequent data communication setups which may increase response times from a user's perspective. FIG. 1 shows the overall principle of powering a modem or transceiver unit of a mobile terminal device in connection with a data communication. From t0 to t1 the terminal device is in idle mode and consumes idle mode power P0. At t1 a data communication activity is started. The modem is powered and the mobile device consumes a significantly higher amount of energy indicated by P2. In the time from t1 to t2 data is communicated via the modem. The time between t1 and t2 depends on the amount of data to be transferred and the data rate. At t2 the data transfer is finalized. However, the modem remains in a powered mode until t3. The time from t2 to t3 depends on a configuration of the mobile terminal device and the network. At t3 the terminal device moves to a power-saving state within a connected mode. In this power-saving state a reduced amount of power P1 is required which is still significantly higher than the power P0 required in idle mode. If no further data communication is required until t4, the data communication connection is closed and the terminal device enters the idle mode. Again, the time from t3 to t4 depends on configurations of the mobile terminal device and the network.
Many data transfer activities between the telecommunication network and the terminal devices are of various background types, for example e-mail updates, messages of social networks, data synchronizations, weather forecast updates, operating system related data, application related data, or updates and so on. This data communication traffic can be relatively frequent in devices performing a diversity of data applications, especially for example smartphones and tablet PCs. A certain portion of this data communication traffic will likely be initiated by servers or services of the telecommunication network rather than the terminal device itself. This means for example that an incoming e-mail could be notified by means of so-called push notifications rather than the terminal device polling for a new e-mail status. Also many other kinds of update services can be push-based, that means that these services are initiated by the telecommunication network and not by the terminal device itself.
In current telecommunication standards, a few features are available supporting saving of battery energy of a terminal device, for example in the 3GPP standard (third generation partnership project), WCDMA (wideband code division multiple access), HSPA (high-speed packet access) and LTE (long-term evolution). For example, for WCDMA/HSPA a fast dormancy signal is available, where a terminal device can transmit a signal after finalizing a data communication session indicating its intention to go into a dormant state. For LTE there is another possibility introduced in release 11 where the terminal device can signal that it wants the network configurations to be as power consumption optimized as possible. This was e.g. studied and proposed in section 6 of 3GPP document 36.822. Furthermore, an introduction of this functionality was part of the “LTE Radio Access Network (RAN) enhancements for diverse data applications”.
However, there is still a need for an improved saving of a battery energy of a terminal device.